* [PATCH net-next] genetlink: correctly begin the iteration over policies
@ 2022-11-08 20:41 Jakub Kicinski
2022-11-08 20:43 ` Jakub Kicinski
2022-11-09 20:10 ` patchwork-bot+netdevbpf
0 siblings, 2 replies; 4+ messages in thread
From: Jakub Kicinski @ 2022-11-08 20:41 UTC (permalink / raw)
To: davem; +Cc: netdev, edumazet, pabeni, Jakub Kicinski, jacob.e.keller
The return value from genl_op_iter_init() only tells us if
there are any policies but to begin the iteration (and therefore
load the first entry) we need to call genl_op_iter_next().
Note that it's safe to call genl_op_iter_next() on a family
with no ops, it will just return false.
This may lead to various crashes, a warning in
netlink_policy_dump_get_policy_idx() when policy is not found
or.. no problem at all if the kmalloc'ed memory happens to be
zeroed.
Fixes: b502b3185cd6 ("genetlink: use iterator in the op to policy map dumping")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
CC: jacob.e.keller@intel.com
Why KASAN doesn't catch the use of uninit memory here is a mystery :S
---
net/netlink/genetlink.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index 362a61179036..9b7dfc45dd67 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -1437,7 +1437,9 @@ static int ctrl_dumppolicy_start(struct netlink_callback *cb)
ctx->op_iter = kmalloc(sizeof(*ctx->op_iter), GFP_KERNEL);
if (!ctx->op_iter)
return -ENOMEM;
- ctx->dump_map = genl_op_iter_init(rt, ctx->op_iter);
+
+ genl_op_iter_init(rt, ctx->op_iter);
+ ctx->dump_map = genl_op_iter_next(ctx->op_iter);
for (genl_op_iter_init(rt, &i); genl_op_iter_next(&i); ) {
if (i.doit.policy) {
--
2.38.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH net-next] genetlink: correctly begin the iteration over policies
2022-11-08 20:41 [PATCH net-next] genetlink: correctly begin the iteration over policies Jakub Kicinski
@ 2022-11-08 20:43 ` Jakub Kicinski
2022-11-08 20:52 ` Keller, Jacob E
2022-11-09 20:10 ` patchwork-bot+netdevbpf
1 sibling, 1 reply; 4+ messages in thread
From: Jakub Kicinski @ 2022-11-08 20:43 UTC (permalink / raw)
To: davem; +Cc: netdev, edumazet, pabeni, jacob.e.keller
On Tue, 8 Nov 2022 12:41:28 -0800 Jakub Kicinski wrote:
> Why KASAN doesn't catch the use of uninit memory here is a mystery :S
Ah, because it's not KMSAN.
^ permalink raw reply [flat|nested] 4+ messages in thread
* RE: [PATCH net-next] genetlink: correctly begin the iteration over policies
2022-11-08 20:43 ` Jakub Kicinski
@ 2022-11-08 20:52 ` Keller, Jacob E
0 siblings, 0 replies; 4+ messages in thread
From: Keller, Jacob E @ 2022-11-08 20:52 UTC (permalink / raw)
To: Jakub Kicinski, davem; +Cc: netdev, edumazet, pabeni
> -----Original Message-----
> From: Jakub Kicinski <kuba@kernel.org>
> Sent: Tuesday, November 8, 2022 12:44 PM
> To: davem@davemloft.net
> Cc: netdev@vger.kernel.org; edumazet@google.com; pabeni@redhat.com;
> Keller, Jacob E <jacob.e.keller@intel.com>
> Subject: Re: [PATCH net-next] genetlink: correctly begin the iteration over policies
>
> On Tue, 8 Nov 2022 12:41:28 -0800 Jakub Kicinski wrote:
> > Why KASAN doesn't catch the use of uninit memory here is a mystery :S
>
> Ah, because it's not KMSAN.
Yea, because KASAN mainly focuses on use-after-free and allocated buffer overruns, while KMSAN focuses on uninitialized memory. It looks like KMSAN isn't yet upstream.
Thanks,
Jake
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH net-next] genetlink: correctly begin the iteration over policies
2022-11-08 20:41 [PATCH net-next] genetlink: correctly begin the iteration over policies Jakub Kicinski
2022-11-08 20:43 ` Jakub Kicinski
@ 2022-11-09 20:10 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 4+ messages in thread
From: patchwork-bot+netdevbpf @ 2022-11-09 20:10 UTC (permalink / raw)
To: Jakub Kicinski; +Cc: davem, netdev, edumazet, pabeni, jacob.e.keller
Hello:
This patch was applied to netdev/net-next.git (master)
by Jakub Kicinski <kuba@kernel.org>:
On Tue, 8 Nov 2022 12:41:28 -0800 you wrote:
> The return value from genl_op_iter_init() only tells us if
> there are any policies but to begin the iteration (and therefore
> load the first entry) we need to call genl_op_iter_next().
> Note that it's safe to call genl_op_iter_next() on a family
> with no ops, it will just return false.
>
> This may lead to various crashes, a warning in
> netlink_policy_dump_get_policy_idx() when policy is not found
> or.. no problem at all if the kmalloc'ed memory happens to be
> zeroed.
>
> [...]
Here is the summary with links:
- [net-next] genetlink: correctly begin the iteration over policies
https://git.kernel.org/netdev/net-next/c/154ba79c9f16
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
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^ permalink raw reply [flat|nested] 4+ messages in thread
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2022-11-08 20:41 [PATCH net-next] genetlink: correctly begin the iteration over policies Jakub Kicinski
2022-11-08 20:43 ` Jakub Kicinski
2022-11-08 20:52 ` Keller, Jacob E
2022-11-09 20:10 ` patchwork-bot+netdevbpf
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